A carwash in Los Angeles was getting a lot of competition from a neighboring carwash which had offered a "guarantee" that went something like this – If it rains within 72-hours, or your car gets dirty again, bring it back for a free wash. So the competitor refused to match this promotional marketing and strategy, and he lost about 33% of his business to the other wash.
So, he decided to go to the mall, find homeless people, and pay them to feed the birds a special concoction which made them crap more often with giant splotches. The mall was right across the street from the other carwash. Obviously, customers kept coming back in for "free-washes" due to giant bird droppings on their cars, so the carwash offering the 72-hour guarantee nixed the idea and modified the offer to read:
I’ve often asked myself why this is, and all I can think of is that it is a "cash" business for the most part, although today most transactions are by credit and debit cards. I think this is why it may have attracted certain types of individuals early on in its history. This has left a historical stigma on the sector, but it has that reputation for good reason in my view. Indeed, I hope you will please consider this and think on it.